The present invention relates generally to an apparatus for controlling the flow of liquids, and in one instance, controlling solvent flow in a parts washer apparatus of the type having a solvent reservoir, a receptacle such as a sink or the like associated with the reservoir for positioning parts to be washed by solvent contained in the reservoir, and a pump and motor for recirculating solvent from the reservoir to the sink.
A typical parts washer with which the invention is useful is a parts washer of the type described in U.S. Pat. No. 3,522,814. This patent discloses a parts washer wherein a sink is positioned atop a barrel-type reservoir and in which a submersible pump in the reservoir circulates solvent from the reservoir to the interior of a sink in which parts are disposed for washing. While the washing is being carried out, solvent continually drains from an opening in the bottom of the sink back into the reservoir sometimes passing through a filter or screen on its way to the reservoir.
Over the years, the most successful parts washers have been those that can be readily and economically serviced. Servicing has consisted of changing the solvent, the filter, if any, and a general machine clean-up. In use, solvent used in a parts washer becomes increasingly dirty until its ability to clean is compromised by the presence of dispersed contaminants and/or soluble oils and greases.
While soluble materials cannot be separated easily except by distillation and hence cannot be removed in situ, particulate matter can be separated, at least to a degree. Some of the particulate matter is of a size such that it readily settles out by gravity; some is entrapped by filtration. Other contaminants of smaller particle size remain suspended indefinitely and circulate with the solvent, compromising its cleaning efficiency, and in some cases, accelerating wear on the pump and/or the pump seals.
For reasons known to those in the industry, it is not practical to subject solvent to very fine mesh filtration, especially considering the construction and operation of most or all mechanical parts washers. The pressure drop across an effective filter of conventional construction is high and good filtration of fine particles cannot be achieved at the required solvent flow rates, because insufficient pressure is available from lightweight, economical submersible pumps.
Regarding the contaminants in the solvent which remain in the reservoir during parts washing, such contaminants tend to be recirculated by the pump because they remain in suspension; in fact, the turbulence created by recirculation tends to re-suspend particles that might separate out under quiescent conditions. In prior art parts washers, the solvent that had just washed the parts in the sink was dumped or splashed into the body of liquid in the reservoir, contributing to turbulence within the body of solvent.
Efforts to permit a solvent to settle at the bottom of the reservoir and to withdraw solvent from the upper portion of the reservoir have not always been successful. The height of the recirculating pump pickup is usually fixed. The level of the upper surface of the solvent tends to vary considerably in depth or height as a result of evaporation, dilution, spillage, and other factors beyond the control of the user. Hence, to be safe, the pump location is usually fixed nearer the bottom of the reservoir.
The problem of separating particulates has been approached by a proposal that a water layer be placed beneath the solvent, allowing solvent to float on top of the water. With such an arrangement, spent solvent is discharged beneath the level of the water layer and allowed to float back to the solvent layer. This is intended to secure cleansing of the solvent by water washing. However, this approach has not been entirely successful, either. Providing a two-phase system involves a certain inevitable amount of emulsifying one liquid within the other. Moreover, any water-based composition tends to create problems of rust, both for the parts which are unintentionally bathed with a minor amount of water and with the containers, to which aqueous systems are more destructive than solvent.
Recently, a successful approach to the problem has been suggested, which approach comprises chemically treating the solvent in such a way as to enhance sedimentation of particulate matter and accelerate its deposition on the bottom of the mass of material. However, there is a delicate balance at work in such systems and mechanical agitation can often compromise the effectiveness of a separation method.
The present invention involves the discovery that cleaning action consistent with long life can be achieved by mechanically separating the reservoir into contaminant-rich and relatively clean portions, and controlling the return of circulated solvent to the reservoir through a drain mechanism constructed and arranged so as to enhance settlement of particulates and to provide two separate, preferably quiescent regions--one where the solid contaminants can remain undisturbed, thus allowing effective settling, and a relatively clean second region adjacent the pump that picks up the solvent for recirculation.
According to this concept, the system includes a drain tube that communicates with the sink opening at one end and terminates at the other end in an opening in a divider plate. The divider plate may but need not have its outer edges spaced just apart from the outer sidewall of the reservoir. A deflector plate is placed beneath the drain opening in the divider plate and spaced vertically therefrom a short distance, whereby solvent passing vertically through the lower drain tube opening is directed radially outwardly. This radial flow action enhances the settling tendencies of any particulate material in the returning solvent by the reduction in velocity of the flow and resultant reduction in particle entrainment and retention. The particulates remain on the reservoir bottom as a sediment layer, isolated from the flowing solvent by the deflector plate. The overall level of solvent is maintained as the clarified solvent slowly rises from the first quiescent region above the sediment layer and passes by or around the divider plate and into the second zone in which the pump is positioned.
In view of the inability of the prior art to provide an effective isolating action for separating a contaminant-rich liquid such as cleaning solvent from contaminant-free solvent, it is an object of the present invention to provide an improved mechanical parts washer having such a separating action.
Another object of the invention is to provide an improved parts washer that is simple to construct and reliable in operation.
Yet another object of the invention is to provide an improved parts washer which includes a combination divider plate and flow deflector assembly adapted to create particular flow patterns tending to minimize turbulence within the body of the solvent in the reservoir.
A further object of the invention is to provide a parts washer wherein the sink drain communicates with a tube terminating at its lower end in a divider plate with a center aperture therein, and wherein a deflector creates and maintains a horizontal flow of fluid passing through the aperture, thus allowing particles to settle into the bottom of the body of solvent in the reservoir.
A still further object of the invention is to provide a drain flow arrangement for a parts washer wherein the divider plate may be adjustably positioned relative to the remaining elements of the apparatus to facilitate effective division of the mass of solvent in the reservoir into separate, quiescent spaces.
An additional object of the invention is to provide a parts washer apparatus having an improved separation mechanism and one which may also be readily serviced and economically manufactured, in order to provide or enhance a favorable contaminant settling action.
A further object of the invention is to provide a parts washer that works effectively with ordinary solvent and also with solvent that may be capable of enhanced particle separation and settling action, and which also operates well with aqueous liquids.
Another object of the invention is to provide an apparatus which will lengthen the service interval required of parts washers by extending the effective cleaning life of the solvent.
Yet another object of the invention is to provide an apparatus which will ensure that solvent from which contaminants have settled remains clarified and free of contaminants during circulation of the remainder of the solvent over the parts being cleaned.
The foregoing and other advantages and objects of the invention are achieved in practice by providing a combination liquid drain, divider and deflector assembly including a drain tube having an upper end positionable adjacent the outlet of a sink or other source for recirculated liquids, a lower end portion immersed within a body of solvent, with a divider plate surrounding the opening adjacent the lower end of the downtube and extending generally radially outwardly a given distance, and a deflector unit positioned below and slightly spaced apart from said divider plate, with the deflector being imperforate and being positioned such that there is a circumferentially extending transfer passage defined between a lower surface of the divider plate and the outer margin of the deflector, whereby liquids flowing down the drain tube and through the outlet thereof are diverted horizontally and whereby the divider plate prevents turbulence created by return flow from being propagated upwardly of the divider plate. In use, the change of solvent flow direction from vertical to horizontal accelerates deposition of particulate matter within the liquid and enhances the separation of higher density particles from the body of the liquid.
The objects and advantages of the invention are also achieved by using the improved drain unit in association with a pump and motor disposed below the level of the liquid and above and radially inwardly of the outer margin of the divider plate.
The exact manner in which the foregoing and other objects and advantages of the invention are achieved in practice will become more clearly apparent when reference is made to the following detailed description of the preferred embodiments of the invention set forth by way of example and shown in the accompanying drawings, in which like reference numbers indicate the corresponding parts throughout.